Today's Message Index:
----------------------
0. 12:21 AM - PLEASE READ - Matronics Email List Fund Raiser During November! (Matt Dralle)
1. 05:06 AM - Re: Alternator without a Battery (Robert L. Nuckolls, III)
2. 05:13 AM - Re: Aviation intercom (Robert L. Nuckolls, III)
3. 05:31 AM - Re: A&P Student Battery/Starter Contactor Question (Robert L. Nuckolls, III)
4. 05:33 AM - Re: Aviation intercom (Harley)
5. 05:38 AM - Re: Contactors (Robert L. Nuckolls, III)
6. 05:38 AM - Re: Contactors (Robert L. Nuckolls, III)
7. 05:54 AM - Re: Aviation intercom (R. curtis)
8. 05:55 AM - Contactors (Robert L. Nuckolls, III)
9. 07:20 AM - Watts on resistors (Carlos Trigo)
10. 08:16 AM - Re: Watts on resistors (R. curtis)
11. 08:33 AM - Re: Watts on resistors (Henador Titzoff)
12. 08:40 AM - Re: Watts on resistors (Robert L. Nuckolls, III)
13. 08:42 AM - Re: Watts on resistors (Robert L. Nuckolls, III)
14. 08:48 AM - Re: Watts on resistors (Peter Pengilly)
15. 08:48 AM - Re: Watts on resistors (Tim Andres)
16. 10:25 AM - Re: Watts on resistors (Robert L. Nuckolls, III)
17. 10:34 AM - Re: Contactors (Sacha)
18. 10:45 AM - Re: Contactors (Sacha)
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Subject: | PLEASE READ - Matronics Email List Fund Raiser During |
November!
Dear Listers,
Each November I hold a PBS-like fund raiser to support the continued operation
and upgrade of the Email List and Fourm Services at Matronics. It's solely through
the Contributions of List members (you) that these Matronics Lists are possible.
You have probably noticed that there are no banner ads or pop-up windows on any of the Matronics Lists or related web sites such as the Forums site http://forums.matronics.com , Wiki site http://wiki.matronics.com , or other related pages such as the List Search Engine http://www.matronics.com/search , List Browse http://www.matronics.com/listbrowse , etc. This is because I believe in a List experience that is completely about the sport we all enjoy - namely Airplanes and not about annoying advertisements.
During the month of November I will be sending out List messages every couple of
days reminding everyone that the Fund Raiser is underway. I ask for your patience
and understanding during the Fund Raiser and throughout these regular messages.
The Fund Raiser is only financial support mechanism I have to pay all
of the bills associated with running these lists. YOUR personal Contribution
counts!
This year we have a really HUGE and TERRIFIC line up of free gifts to go along
with the various Contribution levels. In fact, there are over 30 different gifts
to choose from - more than we've ever had before! There's something for everyone,
to be sure. Most all of these gifts have been provided by some of the
vary members and vendors that you'll find on the Matronics Lists and they have
been either donated or provided at substantially discounted rates.
This year, these generous members include:
Andy Gold of the Builder's Bookstore http://www.buildersbooks.com
Bob Nuckolls of the AeroElectric Connection http://www.aeroelectric.com
Corbin Glowacki of My Pilot Store http://www.mypilotstore.com
George Race of Race Consulting http://www.mrrace.com/
Jon Croke of HomebuiltHELP http://www.homebuilthelp.com
These are very generous guys and I encourage you to visit their respective web
sites. Each one offers a unique and excellent aviation-related product line.
I would like publicly to thank Andy, Bob, Corbin, George, and Jon their generous
support of the Lists again this year!!
Please make your List Contribution using any one of three secure methods including
using a credit card, PayPal, or by personal check. All three methods afford
you the opportunity to select one of this year's free gifts with a qualifying
Contribution amount!!
To make your Contribution, please visit the secure web site:
http://www.matronics.com/contribution
I would like to thank everyone in advance for their generous financial AND moral
support over the years!
Thank you!
Matt Dralle
Matronics Email List Administrator
RV-4/RV-6/RV-8 Builder/Rebuilder/Pilot
Message 1
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Subject: | Re: Alternator without a Battery |
At 09:21 PM 10/30/2013, you wrote:
<tomblejwas@yahoo.com>
Bob,
It has taken days for me to respond because I couldn't get the
website to respond to my enquiries and, consequently, I was unable to
open your new drawing. Today I could! Thanks for your response.
No problem. I started at Cessna last Monday
and the IT Spirits have yet to honor me with
a CAT5 portal to the outside world . . . So
I've been 'disconnected' to some degree as
well . . .
You state that you wouldn't shut down a battery unless there is smoke
in the cockpit and, in which case you would shut down the alternator
as well. If a battery is shorting and drawing more and more current
from the alternator, why wouldn't you disconnect it or do you
consider this too unlikely to design against?
First, how does such a fault become known
to you? You would need a battery-specific
ammeter combined with a bus voltage indicator
combined with the skills to monitor and
interpret those readings for signs of failure.
You ask why two batteries? I'm reconsidering. If the battery can be
disconnected and the engine continues to run on only the alternator,
then one battery probably meets my design goals. Thanks for the question.
A design goal for discussions on this List is
to identify drivers of risk based on useful
study and exploitation of the physics.
As you suggested, I've looked at your new drawing, but I don't think
it meets all my design goals. A shorted battery can't be
disconnected. I'll continue to study it w.r.t my other design goals. Thanks.
Have you identified any instance where a 'shorted
battery' took a system down? A battery is like
a house plant. Given attention tailored to its
needs, it will thrive and perform with great
predictability . . . and reliability. Instances
of battery failure are generally driven by failure
to track the battery's condition and to service
or replace it when performance falls below limits.
I've not heard the phrase "shorted battery" uttered
or written over the course of my career where the
battery was not first subjected to abuses of
poor system architecture and/or poorly implemented
operation and maintenance.
We're encouraged to change oil, plugs, add
magic potions, install engine analyzers, and
read voraciously from every author that claims
to offer words of wisdom for getting the most
from an engine. Now the battery is becoming
an integral component of the system that spins
the prop. I suggest that it be treated with
no less curiosity and respect for capabilities
and limits than your engine.
I will suggest that design goals for your system
include crafting and implementation of an
architecture and maintenance that recognizes
the role of the battery and optimizes conditions
for it to perform.
Bob . . .
Message 2
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Subject: | Re: Aviation intercom |
At 07:30 PM 10/31/2013, you wrote:
>Does anyone have the schematic or Manual for the WGA Model AIR-1177
>Aviation Intercom System? I am trying to figure out the input and
>output jacks on the box. I intend to mount it in a panel along with
>an isolation amp.
>
>Roger
I've not been able to find this product on the 'net.
Where did you find this critter?
Bob . . .
Message 3
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Subject: | Re: A&P Student Battery/Starter Contactor Question |
At 07:44 PM 10/31/2013, you wrote:
Dear Bob,
I just finished a very nice conversation with Bill Bainbridge at B
and C Specialty Products, following through with a question to his
company that I had sent through his website. I learned a great deal
from Bill, though he's referred me to you for what was my initial
question. Here was the original question:
Hi Folks,
I'm an A&P student at Miramar College in San Diego. I'm researching
battery contactors and starter contactors, and haven't been able to
figure out why battery contactors are negatively-controlled, and
starter contactors are positively-controlled. Why can't both of them,
(with slightly different wiring) both be, say, positively controlled?
Is there some historical reason or some technical reason? I would so
appreciate your expertise, as I heard you have a lot of expertise
(from Lyle at Gibbs Repair Station here in San Diego). Thanks so much
for your time. Regards.
Bob, I've been reading through your FAQ's on contactors on your
website--I'm learning much more than we learn in our A & P textbooks!
However, I haven't quite been able to piece together the information
for my answer. I think if I'm out in the bush wiring a plane together
and I have two battery contactors and no starter contactor (as my
instructor says... A & P Mechanics are the smartest people in the
world, and they'll figure out a way to do something...:-)...) that's
when I wonder why they are electrically wired differently.
Hi Lisa,
I don't know that there was any great
debate for the realization of design goals
beyond simplicity and convenience.
Doing a pull-down circuit on a battery
contactor is simpler. One could bring a wire
off the hot side of a contactor into the
cockpit mounted battery switch and back out
to a pull-up terminal of a contactor
coil . . . twice the wire and you need to fuse
the hot end of the supply wire.
I've seen starter contactors wired as a
"pull to ground" control system, just
no on airplanes. The legacy off-l-r-both-start
key-switch could be wired to utilize a
starter contactor with either pull-down or
pull-up control. Power to control the
starter contactor is already available from a
bus in the cockpit so you don't have twice the
wire . . . but you DO need circuit protection
off the bus.
It might have some roots in a system safety
decision. A starter pull-down control line on
a starter contactor is more likely to become
faulted to ground and initiate unintended
starter operation. A pull-up control line is
less likely to get faulted to a source of
power.
The short answer to your question does not
offer insights into any great thinking on the
part of designers who adopted these conventions
100 years ago. Designers in those days were
probably not into reliability studies of
probability for hazardous failure.
Bob . . .
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Subject: | Re: Aviation intercom |
Bob (and Roger)...
I found the intercom on the maker's website, (
www.warrengregoire.com/aviation-intercoms.htm ) but no manuals or
schematics there.
However, there is contact information:
*
Warren Gregoire and Associates LLC*
FOR PILOTS AND AIRCRAFT OWNERS
1933 Davis Street, Suite 276, San Leandro, CA 94577, USA
HOURS*
*7:00 am - 7:00 pm PST, 7 days a week/365 days a year
_
_TELEPHONES*
*/*TOLL-FREE*/ *1-800-634-0094* - USA and Canada
510-633-9353 - All Other Countries
510-633-9355 - FAX
INTERNET*
*warrengregoire@hotmail.com <mailto:warrengregoire@hotmail.com>-
Questions?
warrengregoire@hotmail.com <mailto:warrengregoire@hotmail.com>-
Sales Department
Harley Dixon
-----------------------------------------------------------------
On 11/1/2013 8:13 AM, Robert L. Nuckolls, III wrote:
> At 07:30 PM 10/31/2013, you wrote:
>> Does anyone have the schematic or Manual for the WGA Model
>> AIR-1177 Aviation Intercom System? I am trying to figure out
>> the input and output jacks on the box. I intend to mount it
>> in a panel along with an isolation amp.
>>
>> Roger
>
> I've not been able to find this product on the 'net.
> Where did you find this critter?
>
>
> Bob . . .
>
> *
> *
Message 5
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At 12:10 AM 11/1/2013, you wrote:
>
>I use automotive "cube" relays (one for the master relay, one for
>alternator) rated at 70A. They are light and consume less than 300mA
>each. Is there a reason not to use them? The only potential
>drawback I'm aware of is that they can break the contact if subject
>to violent shocks. But loosing panel power for a few milliseconds
>doesn't seem such a big issue (the autopilot does reset but then in
>such violent turbulence you might be hand flying the thing in any
>case, and the GNS430 doesn't even notice any absence of power that
>lasts that little).
>
>Are there other risks I am not considering here? This is a VFR only
>machine and I'm a low time PPL so not the most experienced in these matters.
The legacy battery contactor is tasked with
carrying normal operating loads usually in
the tens of amps but predicated on getting an
engine started . . . loads of perhaps 200A.
Hence the selection of contactors that seem
unnecessarily oversized to the task. But the
one device can do it all. Some of the designs
we're considering DO add smaller relays which
function as a mini-contactor to handle loads
other than starting and/or battery recharging.
Bob . . .
Message 6
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At 12:21 AM 11/1/2013, you wrote:
>Sacha,
>I have used one of these Bosch 70amp relays for the master in my
>experimental Bonanza for the past 8 years - rock solid! I still use
>the caveman relay for the starter.
>
>Bob Verwey
>A35 ZU-DLW
But you don't crank the engine through it do you?
Bob . . .
Message 7
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Subject: | Re: Aviation intercom |
Does anyone have the schematic or Manual for the WGA Model AIR-1177 Aviatio
n Intercom System=3F I am trying to figure out the input and output jacks on
the box. I intend to mount it in a panel along with an isolation amp.
I've not been able to find this product on the 'net.
Where did you find this critter=3F
A Google search brings it right up: http://www.warrengregoire.com/aviation-
intercoms.htm
Roger
--
Do you have a slow PC=3F Try a Free scan http://www.spamfighter.com/SLOW-PCfi
ghter=3Fcid=sigen
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From my newly acquired perch within the halls
of Cessna Engineering I've discovered that the
battery and starter contactors used on the single
engine fleet have pretty much always been in the
same style and ratings as the Cole-Hersee, RBM,
Stancore, White-Rogers devices we've been discussing
here on the List.
Before the Great Shut-Down, Cessna purchased individual
contactors for installation on the line. After the
Great Resurrection, the contactors came to Cessna as
part of a power distribution box mounting up to
4 such contactors. Battery, starter, alternator, ground-
power. Of course, they're all 24 volt devices.
During my earlier tenure at Cessna (64-69) the starter
contactors were a low-duty cycle version of the battery
contactor. They left something to be desired as SWITCHING
devices for starter currents. I suspect that the
modern starter contactors have exploited discoveries
common to contemporary automotive starter contactors
for small area, very high pressure contacts.
http://tinyurl.com/96wy5mq
Yes, there have been some serviceability issues managed
by some modifications to the contact materials, springs,
etc. etc. But the general configuration of the modern
contactor has changed little since 1948. But in particular,
there's no reason to believe that the modern encarnation
of the 70 series device is any less suited to task
as a battery contactor than it has been for many years.
I dug up a 1960 copy of an Allied Electronics catalog
hoping to discover the price of these devices back then.
They don't appear in that catalog.
Bob . . .
Message 9
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Subject: | Watts on resistors |
Bob and all
The VP-X Pro installation manual recomends, in order to have Volt indication from
the Aux Batt, to connect the + terminal to a certain pin in the box, trough
a 1Kohm - 1W resistor.
Problem is that I can only find 1Kohm - 2W resistor. So, to learn something else
today, can someone please explain if there is any problem if I use the 2W instead
of 1W resistor.
(Please don't answer indicating a source for 1W resistors...)
Regards
Carlos
Message 10
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Subject: | Re: Watts on resistors |
> Problem is that I can only find 1Kohm - 2W resistor. So, to learn
> something else today, can someone please explain if there is any problem
> if I use the 2W instead of 1W resistor.
The 2 watt resistor will work exactly the same in the circuit as a 1
watt.
The only difference is that the 2 watt is somewhat larger with more
surface
area and can dissipate more heat without burning up.
Roger
--
Do you have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
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Subject: | Re: Watts on resistors |
It should be no problem, Carlos, as long as you have enough room and the circuit
isn't frequency sensitive. Wattage is the resistor's ability to dissipate heat,
and the resistor is bigger as the wattage goes up.
Henador Titzoff
--------------------------------------------
On Fri, 11/1/13, Carlos Trigo <trigo@mail.telepac.pt> wrote:
Subject: AeroElectric-List: Watts on resistors
To: "aeroelectric-list@matronics.com" <aeroelectric-list@matronics.com>
Date: Friday, November 1, 2013, 7:21 AM
--> AeroElectric-List message
posted by: Carlos Trigo <trigo@mail.telepac.pt>
Bob and all
The VP-X Pro installation manual recomends, in order to have
Volt indication from the Aux Batt, to connect the + terminal
to a certain pin in the box, trough a 1Kohm - 1W resistor.
Problem is that I can only find 1Kohm - 2W resistor. So, to
learn something else today, can someone please explain if
there is any problem if I use the 2W instead of 1W
resistor.
(Please don't answer indicating a source for 1W
resistors...)
Regards
Carlos
Lists This Month --
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Raiser. Click on
more about
Gifts provided
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-Matt
Dralle, List Admin.
AeroElectric-List Email Forum -
- MATRONICS WEB FORUMS -
Message 12
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Subject: | Re: Watts on resistors |
At 09:21 AM 11/1/2013, you wrote:
>
>Bob and all
>
>The VP-X Pro installation manual recomends, in order to have Volt
>indication from the Aux Batt, to connect the + terminal to a certain
>pin in the box, trough a 1Kohm - 1W resistor.
>Problem is that I can only find 1Kohm - 2W resistor. So, to learn
>something else today, can someone please explain if there is any
>problem if I use the 2W instead of 1W resistor.
>(Please don't answer indicating a source for 1W resistors...)
That's an easy one.
The resistor is a substitute for a fuse. Further,
it's called out as 1-watt for mechanical convenience
and robustness. Examples:
Some years back I suggested that the most valuable
and often least accessible data point for diagnosing
an alternator problem is to watch FIELD VOLTAGE
behavior while putting an alternator through
its paces.
I published this little feature in Z-23 suggesting
a permanently attached wire PROTECTED by a resistor
leading from the alternator field to some handy point
in the cockpit.
Emacs!
A fuse would be okay too. A 1/4 watt would work but 1/2
watt was mechanically more robust, 1w would have
been better yet. So as long as you don't mind a larger
'lump' in your battery sense lead, a 2W resistor is
okay as well.
http://tinyurl.com/kyc6tq6
I think it was here on the List that I once suggested
a tubular, 10-watt wire wound resistor with flag
terminals as a suitable enclosure for a reed switch
current sensor.
Emacs!
The 'jeep' was to put lead wires on the reed switch
then epoxy into place down the center of the tubular
resistor. Then wind an excitation coil around the
center of the resistor over the reed. Calibrate
closure current for the reed by adjusting coil
turns.
In this case, the actual value of the resistor
wasn't critical . . . just needed to be high
enough not to adversely affect current through
the the coil. The resistor became a robust
'housing' for the current sense relay offering
a convenient terminals to tie off ends
of the coil.
These are but two examples of many where the
designer's 'sizing' of a component may not
have obvious foundation in the original
design goals for the part.
Bob . . .
Message 13
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Subject: | Re: Watts on resistors |
> The VP-X Pro installation manual recomends, in order to have
> Volt indication from the Aux Batt, to connect the + terminal
> to a certain pin in the box, trough a 1Kohm - 1W resistor.
Hmmm . . . I think Marc harvested that concept for
sense wire protection off of Z-23.
Bob . . .
Message 14
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Subject: | Re: Watts on resistors |
Hi Carlos,
My view is 2W will be fine - it means that the resistor will cope with a
higher voltage (45v) & so dissipate more energy. A 1W resistor will cope
with 32v (theoretically).
Peter
On 01/11/2013 14:21, Carlos Trigo wrote:
>
> Bob and all
>
> The VP-X Pro installation manual recomends, in order to have Volt indication
from the Aux Batt, to connect the + terminal to a certain pin in the box, trough
a 1Kohm - 1W resistor.
> Problem is that I can only find 1Kohm - 2W resistor. So, to learn something else
today, can someone please explain if there is any problem if I use the 2W
instead of 1W resistor.
> (Please don't answer indicating a source for 1W resistors...)
>
> Regards
> Carlos
>
>
Message 15
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Subject: | Re: Watts on resistors |
So it sounds like they are using a resistor to protect the sensor wire from over
current/unintentional ground instead of a fuse, is that the purpose here?
Tim
> On Nov 1, 2013, at 8:15 AM, "R. curtis" <mrspudandcompany@verizon.net> wrote:
>
>
>> Problem is that I can only find 1Kohm - 2W resistor. So, to learn something
else today, can someone please explain if there is any problem if I use the 2W
instead of 1W resistor.
>
> The 2 watt resistor will work exactly the same in the circuit as a 1 watt.
> The only difference is that the 2 watt is somewhat larger with more surface
> area and can dissipate more heat without burning up.
>
> Roger
>
> --
>
> Do you have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
>
>
>
>
>
>
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Subject: | Re: Watts on resistors |
At 10:48 AM 11/1/2013, you wrote:
>
>So it sounds like they are using a resistor to protect the sensor
>wire from over current/unintentional ground instead of a fuse, is
>that the purpose here?
>Tim
Exactly. The input impedance to the instrumentation
system is either sufficiently large that added
1K of resistance is insignificant . . . or is a
calculated part of the input voltage divider.
Bob . . .
Message 17
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>>> Sacha,
>>> I have used one of these Bosch 70amp relays for the master in my experimental
Bonanza for the past 8 years - rock solid! I still use the caveman relay for
the starter.
>>>
>>> Bob Verwey
>>> A35 ZU-DLW
>>
Thanks Bob V for the validation.
>> But you don't crank the engine through it do you?
No, the starter contactor is not the automotive type.
Message 18
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On Nov 1, 2013, at 13:37, "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
wrote:
>
> At 12:10 AM 11/1/2013, you wrote:
>>
>> I use automotive "cube" relays (one for the master relay, one for alternator)
rated at 70A. They are light and consume less than 300mA each. Is there a reason
not to use them? The only potential drawback I'm aware of is that they can
break the contact if subject to violent shocks. But loosing panel power for
a few milliseconds doesn't seem such a big issue (the autopilot does reset but
then in such violent turbulence you might be hand flying the thing in any case,
and the GNS430 doesn't even notice any absence of power that lasts that little).
>>
>> Are there other risks I am not considering here? This is a VFR only machine
and I'm a low time PPL so not the most experienced in these matters.
>
> The legacy battery contactor is tasked with
> carrying normal operating loads usually in
> the tens of amps but predicated on getting an
> engine started . . . loads of perhaps 200A.
Ah. Ok now I understand your previous question. In my case the fat wire to the
starter contactor is always hot. The master just activates the coil circuit.
I now know this is against conventional design where master OFF is supposed to
correspond to max darkness. In my case the total length of fat (positive) wire
is approx 50cm (20"): battery to starter contactor to starter motor.
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